Polysilicon resistors are widely used in conventional integrated circuit design, including for RC oscillators, current limitation resistance, ESD protect, RF post drivers, on-chip termination, impedance matching, etc. For replacement gate technology, the polysilicon resistor typically includes a silicide region, which exhibits lower than desirable resistivity, and accordingly requires higher than desirable area overhead. A single crystalline silicon resistor (e.g., a resistor formed in a semiconductor substrate) has been proposed to resolve this issue, however, the single crystalline silicon resistor fails to provide precise impedance matching and capacitance for analog circuits, such as radio frequency and mixed-mode circuits.
Polysilicon electronic fuses (eFuses) are widely used in conventional memory integrated circuit design. See, e.g., U.S. Pat. No. 7,098,721 B1, entitled “Low Voltage Programmable eFuse with Differential Sensing Scheme” issued to Ouellette et al., and U.S. Publication No. 2007/0099326 A1, entitled “eFuse and Methods of Manufacturing the Same” issued to Hsu et al., which are hereby incorporated by reference. Similarly, for replacement gate technology, the polysilicon eFuse exhibits lower than desirable resistivity. Contact, via, and copper metal has been proposed to resolve this issue, however, such proposals fail to address programming voltage issues, for example, the need to lower the programming voltage while maintaining a high resistance.
Accordingly, what is needed are semiconductor devices that addresses the above stated issues, and methods for making such semiconductor devices.